Noises from your baseboard heat can be caused by a number of things, even though it is actually very common and can be ignored unless the system itself does not function well while making such noise. These things include, pipes that need to be bleed and also incorrect installation of slant fin heat will also cause noise.
The first step would be to determine what type of noise it is. If it sounds like "water rolling through the pipes" you probably will need to have your boiler bleed as there might be too much air trapped in the system. You can check this air level by examining the pressure gauge on the boiler unit, and it should be between 12 and 20 PSI. If it’s out of that range, you will need to contact a professional plumber to fix it.
If zone valve closes too quickly, and then it creates a pressure which will bounce back to the air in the system and eventually force the valve to open again. This will make a loud banging sound in the boiler system.
If the noise sounds like clicking, or plucking, it means that the grey clips on not postioned in the right place.
To correct this adjust the baseboard clips under the fins.
There are metal fins located inside the covers and they will make a pinging noise when they start rubbing against each other. First you will need to examine if they are bent or crushed, and fix them by straighten them carefully. Also you can slide small pieces of wax papers in between the fins so that they don’t touch the baseboard unit.
Knocking or Hammering Sound?
When the cold water enters the boiler, it will be heated and becomes hot water. Then the circulation starts through the pipes and due to this heat, the expansion of the pipes will occur and thus making this “knocking” sound as the expanded pipe begins to rub against the floor. To muffle this knocking sound yourself, you could try placing a folded wax papers or thin layer of insulators in between the pipes. It would be acting as a mediator between the pipes.
If you hear a hammering sound – such as hitting pipes with a hammer repeatedly – then it could be possible that the temperature in the hot water boiler becomes overheat.
You may also want to try to set the boiler temperature setting to lower levels at the beginning of the periods. This will actually make the water circulating longer at a lower temperature while reducing the contraction and expansion of the pipes.